Closed fluid loops are used in cooling electronic devices, such as microprocessors in a computer. The fluid loop includes a heat exchanger which is placed in contact with the microprocessor as well as a heat rejector and pump coupled to the heat exchanger by one or more fluid tubes. FIG. 1 illustrates an existing fluid loop assembly 10. As shown in FIG. 1, the assembly 10 includes the heat exchanger 12 having a protruding tongue 14 and a pair of attach legs 20 extending from the body of the heat exchanger 12. In addition, the assembly 10 includes a substantially larger heat rejector 16 that is coupled to the heat exchanger 12 by three fluid tubes 18, whereby the heat rejector 16 includes a pair of attach legs 24 extending therefrom. The components in the assembly 10 are rigidly connected to one another to form one rigid assembly 10. As shown in FIG. 1, the microprocessor 26 is attached to a printed circuit board 22 by conventional means. The heat exchanger 12 of the assembly 10 is placed in contact with the microprocessor 26 and secured thereto by inserting the tongue 14 under a retaining member 28 and screwing the attach legs 20 into the printed circuit board 22 using screws 99. In addition, the attach legs 24 of the heat rejector 16 are also screwed into the printed circuit board 22 using screws 99. The system 10 is thereby rigidly attached to the printed circuit board 22 at several locations 24, 28 with very stiff mounting elements.
Closed loop cooling systems are required to retain fluid and vapor during extended operation. Ordinary flexible tubing made from rubber, silicone, plastics, or other highly-flexible materials are incapable of retaining fluids and vapors for extended periods. To overcome this deficiency, the materials of the tubing and fluidic connections includes metals, ceramics, glasses, and other impermeable materials and structures. Such materials and designs of the tubing and fluidic connections share the characteristic in that they are very stiff and cannot be flexed without cracking the cooling system or damaging the electronic system.
In the event of sudden deceleration, shock or bending force applied to the system or the circuit board 22, the stiff, fixed mounts are subjected to very large concentrated stresses which may crack the circuit board 22 or damage the cooling system. During the assembly process, it is common for the fasteners between the system and the printed circuit board to be applied sequentially. As a result, the cooling system will shift and/or tilt some amount of distance at various moments during the assembly process, thereby causing the gap between the microprocessor and the heat exchanger to increase momentarily. Additionally, during the process of attaching the cooling system 10 to the circuit board 22, dimensional tolerances in the components may lead to slightly bent or misaligned components along the circuit board 22. In this case, the stiff mounting structures will lead to very large concentrated stresses between the components that might damage the mounting point, crack the circuit board, or damage the cooling system. These stresses can lead to torque on the heat exchanger element 12 and slight gaps forming between the heat exchanger 12 and the microprocessor 26. The fluid tubes 18 which connect the heat exchanger 12 to the heat rejector 16 are rigid and cannot move independently of one another with respect to the circuit board. In other words, the components of the assembly 10 do not incorporate any tolerance and are not flexible to respond to sudden movements. The stiffness and rigidity of the assembly 10 in FIG. 1 thus makes the assembly 10 susceptible to cracking or breaking whenever the printed circuit board 22 or entire packaging undergoes sudden movements or is dropped. In addition, the inability of the individual components in the assembly 10 to independently move or tolerate movement often causes the heat exchanger 12 to come out of or lose contact with the microprocessor 26 when subjected to sudden movements. Additionally, sudden movements experienced by the assembly 10 may cause the heat grease or thermal interface material between the heat exchanger 12 and microprocessor 26 to move, thereby making the heat exchanger 12 less effective in removing heat from the microprocessor 26. Any of the above scenarios can be detrimental to the electronic device packaging utilizing the closed fluid loop within.
What is needed is an assembly for coupling a closed loop fluid system to a mounting surface in which the individual components are decoupled and able to move independently with respect to one another. What is also needed is an assembly which secures and maintains all necessary interface contacts to retain the integrity of the cooling system. What is also needed is an assembly configured to apply force which is approximately constant and maintains the heat exchanger in consistent contact with the electronic device irrespective of sudden movements are shocks applied to the system.